Patent Literature 1 is a prior art vehicle slide rail device, which is provided with a pair of left and right lower rails which are fixed to a vehicle interior floor, extend in the forward/rearward direction and include a large number of lock grooves arranged in a forward/rearward direction; a pair of left and right upper rails which support a seating portion of a seat and are slidably supported by the left and right lower rails; lock springs, supported by the upper rails and each having a locking portion which is disengageably-engageable with the lock grooves from below; and lock-release levers which are respectively supported by the upper rails so that the lock-release levers are rotatable between a locked position, at which the lock-release levers do not act on the lock springs, and an unlocked position, at which the lock-release levers act on the lock springs to eject each locking portion from the corresponding lock groove.
In this slide rail device, when an occupant applies no operating force to the lock-release levers, the slide position of the seat and upper rails with respect to the lower rails is maintained by the locking portion of each lock spring engaging with one of the lock grooves. On the other hand, upon an occupant rotating the lock-release levers to the unlocked position against the biasing force of the lock springs, the locking portion of each lock spring disengages from the associated lock groove to thereby allow the seat and the upper rails to slide with respect to the lower rails.